Question

Find the 20th term from the last term of the A.P. 3, 8, 13,.....,253​

Answer 1

Step-by-step explanation:

a=3 d=5 last term =253

nth term= a+(n-1)d

253=3+(n-1)5

253=3+5n-5

253=-2+5n

255=5n

n=51

20th term= a+(n-1)d

=3+(20-1)5

=3+(19)5= 3+95=98

Answer 2

Answer:

158

Step-by-step explanation:

Given,

3, 8, 13,.....,253​

To Find,

20th term from the last term.

Solution,

l = Last term = 253

d = Common difference = 8 - 3 = 5

∴ 20th term from the end = l - (20 - 1)d

==> l - 19d

==> 253 - 19 × 5

==> 253 - 95

==> 158

Result:

20th term = 158